<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>
<script>
    var str = '';
    for (var i = 1; i <= 9; i++) { // 外层循环控制行数
        for (var j = 1; j <= i; j++) { // 里层循环控制每一行的个数  j <= i
            // 1 × 2 = 2
            // str = str + '★';
            // str=str+j
            str += j + '×' + i + '=' + i * j + '\t';
        }
        str += '\n';
    }
    console.log(str);
</script>

</html>